Encapsulation of hydrophobic actives is an incredibly important area of research, affecting the personal care, home care, antimicrobial, life science, and agricultural industries. Generally, encapsulation is on the micro scale, and protects the hydrophobic active from decomposition or unwanted interactions with other materials in the formulation, as well as sometimes providing controlled release.
There are a number of conventional encapsulation technologies, such as aqueous polyurethane dispersions, polyurea dispersion, melamine-formaldehyde dispersions, poly(meth)acrylate dispersions, and urea-formaldehyde dispersions, and it is important that the encapsulation efficiency be tested in order to determine where improvement can occur. However, depending on shell thickness and cross-linking chemistry and density, some encapsulated particles are too fragile to be tested by conventional organic solvent extraction methods. It should be understood that testing such particles by conventional methods leads to rupture or release of the hydrophobic active, and hence inaccurate determination of un-encapsulated (or free) hydrophobic active.
Therefore, what is needed are new test methods that are less disruptive.